Tris-organophosphite compositions having improved hydrolytic stability

ABSTRACT

Tris-organophosphite compositions are provided having an improved hydrolytic stability, comprising 
     (1) a tris-organophosphite of the formula: ##STR1## wherein: R 1 , R 2  and R 3  are selected from the group consisting of alkyl, alkenyl, aryl, alkylaryl and aralkyl groups together aggregating at least fourteen carbon atoms up to about sixty carbon atoms; and 
     (2) a long-chain aliphatic amine in an amount to improve the hydrolytic stability of the phosphite and having the formula: ##STR2## wherein: R 4 , R 5  and R 6  are selected from the group consisting of hydrogen; aliphatic (including alkyl and alkenyl) groups having from one to about thirty-six carbon atoms; and hydroxyalkyl having from two to about six carbon atoms; one of R 4 , R 5  and R 6  is an aliphatic group having at least ten carbon atoms, and the remaining of R 4 , R 5  and R 6  are selected from hydrogen, alkyl having from one to four carbon atoms and hydroxyalkyl; and preferably at least one of R 4 , R 5  and R 6  is hydroxyalkyl.

Many organic phosphites have been proposed as stabilizers for polyvinylchloride resins, and are employed either alone or in conjunction withother stabilizing compounds, such as polyvalent metal salts of fattyacids and alkyl phenols. Such phosphite stabilizers normally containalkyl or aryl radicals in sufficient number to satisfy the threevalences of the phosphite, and typical phosphites are described in thepatent literature, for example, W. Leistner et al, U.S. Pat. Nos.2,564,646 of Aug. 14, 1951, 2,716,092 of Aug. 23, 1955 and 2,997,454 ofAug. 2, 1961.

Organic phosphites have also been added as stabilizers in amounts of0.01 to 1%, preferably 0.05% to 0.2% by weight, to high molecular weightpolycarbonate plastics, for example the polycarbonate of2,2'-bis(4-hydroxyphenyl)propane.

Phosphites are also employed in conjunction with other stabilizers suchas a polyhydric phenol in the stabilization of polypropylene and othersynthetic resins against degradation upon heating or ageing underatmospheric conditions. The polyhydric phenol is thought to function asan antioxidant in such combinations.

The importance of organic phosphites as stabilizers for synthetic resinshas led to the development of a large variety of special phosphitesintended to provide improved stabilizing effectiveness and compatibilityand ease of compounding with the resin and with other stabilizerscommonly used.

Among these special phosphites, L. Friedman, U.S. Pat. No. 3,047,608 ofJuly 31, 1962 discloses a class of spiro-biphosphites having theformula: ##STR3## in which R₁ and R₂ are alkyl or aryl.

Hechenbleikner, U.S. Pat. No. 4,290,976, patented Sept. 22, 1981, statesthat dialkyl pentaerythritol diphosphites having the structural formula##STR4## where R and R are alkyl groups have been known for some time aseffective stabilizers for vinyl polymers. They have been used primarilyto stabilize vinyl chloride polymers and polyolefins, but have found usealso in the stabilization of styrene polymers such as ABS.

However, these dialkyl pentaerythritol diphosphites have not beencharacterized by good hydrolytic stability. In a moist environment theytend to undergo hydrolytic decomposition, with a corresponding loss ofpolymer-stabilizing effectiveness. Attempts to solve this problem ofhydrolysis have utilized additives and these have been somewhatsuccessful, but the problem remains, according to Hechenbleikner.

Hodan and Schall, U.S. Pat. No. 3,553,298, patented Jan. 5, 1971suggested that the hydrolytic stability of phosphite esters of a wideclass could be improved by combination therewith of an additive that isnitrogen-containing and selected from the group consisting ofheterocyclic alkyl nitrogen compounds, such as typically piperidine,pyrrolidine, piperazine, diketopiperazine, picoline, anthraquinoline,N-methyl pyrrolidine, thiazole, oxazolidine, isooxazolidine, andoxdiazole; aromatic heterocyclic nitrogen compounds, such as typicallyoxazoline, isoxazoline, thiotriazole, pyridine, picoline, pyrrole, andquinoline; dialkanolamines such as typically diisopropanol amine,diethanol amine, tetraethanol ethylene diamine, and tetraisopropanolethylene diamine; trialkanol amines such as typically triisopropanolamine, and triethanol amine; ammonia; and alkyl amines such as triethylamine, dimethyl amine, and tripropyl amine.

The stabilizer is normally employed in from about 0.01% to about 5% byweight of the phosphite ester, preferably from about 0.2% to about 1%.

York, U.S. Pat. No. 4,116,926, patented Sept. 26, 1978 foundtriisopropanolamine to be a particularly effective stabilizer fordialkylpentaerythritol diphosphites and polyalkyl bisphenol-Apolyphosphites.

The dialkylpentaerythritol diphosphites have the structural formula:##STR5## where R and R' are alkyl groups. The polyalkyl bisphenol-Apolyphosphites have the structural formula: ##STR6## where A and B areeach HOC₆ H₄ C(CH₃)₂ C₆ H₄ O or RO. R is alkyl and n is 1 to 5.

Most alkyl and alkylaryl pentaerythritol-spiro-bis phosphites havingfourteen or more carbon atoms in the alkyl or alkylaryl groups andindeed even pentaerythritol-spiro-bis phosphite itself are solidmaterials. When their melting point is above 40° C., they are readilyreduced to particulate form, and therefore are easily blended with othersolid stabilizers for combination with synthetic resins. When howevertriisopropanolamine is used to improve hydrolytic stability, thedesirable qualities of these pentaerythritol-spiro-bis-phosphites as aneasily-handled particulate solid material are lost, and the material isconverted into a sticky solid that is rather difficult to work with. Itis not readily reduced to particulate form, and when in particulate formtends to agglomerate with itself and with other materials that aresought to be blended therewith, in formulating multicomponent stabilizersystems.

In accordance with Ser. No. 542,923 filed Nov. 28, 1983, long-chainaliphatic amines are shown to be effective in improving the hydrolyticstability of pentaerythritol-spiro-bisphosphites, and in addition arereadily formulated therewith to form nonsticky solid compositions thatare readily reduced to particulate form, and can easily be blended withother stabilizers and with synthetic resins, thus overcoming thestickiness problem inherent in the use of triisopropanolamine.

The pentaerythritol-spiro-bis-phosphite compositions of Ser. No. 542,923having an improved hydrolytic stability consist essentially of

(1) a pentaerythritol-spiro-bis-phosphite having the formula: ##STR7##wherein:

R₁ and R₂ are selected from the group consisting of alkyl and alkylarylgroups having at least fourteen carbon atoms up to about thirty-sixcarbon atoms; and

(2) a long-chain aliphatic amine in an amount to improve the hydrolyticstability of the phosphite and having the formula: ##STR8## wherein:

R₄, R₅ and R₆ are selected from the group consisting of hydrogen;aliphatic (including alkyl and alkenyl) groups having from one to aboutthirty-six carbon atoms; and hydroxyalkyl having from two to about sixcarbon atoms; one of R₄, R₅ and R₆ is an aliphatic group having at leastfourteen carbon atoms, and the remaining R₄, R₅ and R₆ are selected fromhydrogen, alkyl having from one to four carbon atoms and hydroxyalkyl;and preferably at least one of R₄, R₅ and R₆ is hydroxyalkyl.

In accordance with the present invention, it has been determined thatsuch long-chain aliphatic amines also improve the stability oftris-organophosphites of the formula: ##STR9## wherein:

R₁, R₂ and R₃ are selected from the group consisting of alkyl, alkenyl,aryl, alkylaryl and aralkyl groups together aggregating at leastfourteen carbon atoms up to about sixty carbon atoms.

The improvement in hydrolytic stability of the tris-organophosphite isevident with the addition of even small amounts, as little as 0.1%, ofthe aliphatic amine. The improvement increases with the amount of amineadded. In most instances amounts within the range from about 2% to about3.5% and even up to about 10% of the amine give adequate hydrolyticstability for normal use. Such amounts are therefore preferred. Largeramounts of amine can be used but tend to be wasteful and uneconomic.

Exemplary R₄, R₅ and R₆ alkyl groups in the amines include, for example,methyl, ethyl, propyl, isopropyl, butyl, secondary butyl, tertiarybutyl, isobutyl, amyl, isoamyl, secondary amyl, 2,2-dimethyl propyl,tertiary amyl, hexyl, isohexyl, heptyl, octyl, 2-ethyl hexyl, isooctyl,nonyl, isononyl, decyl, isodecyl and lauryl. The following are alsoexemplary of R₁, R₂ and R₃ in the phosphite as well as R₄, R₅ and R₆ inthe amines: myristyl, palmityl, stearyl, oleyl, eicosyl, behenyl,tricosyl, tetracosyl, octacosyl, nonacosyl, triacontyl, hentriacontyl,tritriacontyl, and hexatriacontyl.

R₁, R₂ and R₃ alkaryl and aralkyl groups in the phosphite includebenzyl, phenethyl, phenylpropyl, phenylbutyl, phenylamyl, phenyloctyl,phenylnonyl; methylphenyl, ethylphenyl, propylphenyl, butylphenyl,amylphenyl, tert-butyl phenyl, tert-amyl phenyl, hexyl phenyl,octylphenyl, 2,6-di-t-butyl-4-methylphenyl,2,6-di-t-butyl-4-(methoxycarbonylethyl phenyl, isooctylphenyl,t-octylphenyl, nonylphenyl, 2,4-di-t-butylphenyl, benzylphenyl andphenethylphenyl.

Tris organophosphites include tris-nonyl phenyl phosphite, nonylphenyldi-isopropyl phosphite tri-2-ethylhexyl phosphite, triisodecylphosphite, tris-hexadecyl phosphite, tris-stearyl phosphite, diphenylisooctyl phosphite, di-isodecyl phenyl phosphite,tris(2,4-di-t-butylphenyl)phosphite,tris-(2,6-di-t-butylphenyl)phosphite,tris-(2-t-butyl-4-methylphenyl)phosphite,bis-(2,4-di-t-butyl-6-methylphenyl)octylphenyl phosphite,bis(2,4-di-t-butyl-6-methylphenyl)nonylphenyl phosphite,bis-(2,6-di-t-butyl-4-methylphenyl)phenyl phosphite,bis(2,6-di-t-butyl-4-ethylphenyl)octyl phosphite, nonylphenyl2,6,di-t-butyl-4-methylphenyl-2,6-di-t-butylphenyl phosphite, octyl2,6-di-t-butyl-4-methylphenyl 2,4-di-t-butylphenyl phosphite, dodecyl2,6-di-t-butyl-4-methylphenyl-2,4-di-t-octylphenyl phosphite,tris(2,6-di-t-amyl-4-methylphenyl phosphite,bis(2,6-di-t-amyl-4-methylphenyl)phenyl phosphite,bis(2,6-di-t-octyl-4-methylphenyl)nonylphenyl phosphite, tri-isoamylphosphite, triphenyl phosphite, tri-n-hexyl phosphite, and isodecyldiethyl phosphite.

The tris-organophosphite/long-chain aliphatic amine compositions of theinvention can be prepared by blending the tris-organophosphite and longchain aliphatic amine in any convenient manner. Liquid phosphites can beblended with the aliphatic amine at ambient temperature or warmed gentlyto diminish viscosity and speed up mixing. When the phosphite is solidat ambient temperature and molten below about 110° C., the aliphaticamine is conveniently mixed into the melt before allowing thecomposition to solidify. A relatively high melting phosphite can beblended with the amine with the assistance of a mutual solvent such astoluene or isopropanol. Alternatively, the particulate phosphite can betumbled or agitated with the aliphatic amine in molten or particulateform.

Complete homogenization of the phosphite and amine composition is notessential. In fact, a condition in which a large part of the aliphaticamine is concentrated at or near the surface of solid phosphiteparticles as in a coating or encapsulation desirably maximizes theeffectiveness of the amine when used in modest concentrations, such as5% by weight of the phosphite.

Exemplary alkyl monoalkanol amines, which are a preferred class ofaliphatic amines, include palmityl ethanolamine, lauryl ethanolamine,isodecyl ethanolamine, stearyl ethanolamine, oleyl ethanolamine,myristyl ethanolamine, behenyl ethanolamine, and eicosyl ethanolamine;stearyl propanolamine, palmityl propanolamine, distearylmonoethanolamine, dipalmityl monoethanolamine, dimyristylmonoethanolamine, and myristyl propanolamine.

Exemplary alkyl dialkanol amines, which are also a preferred class ofaliphatic amines, include palmityl diethanolamine, stearyldiethanolamine, oleyl diethanolamine, myristyl diethanolamine, behenyldiethanolamine, eicosyl diethanolamine; stearyl dipropanolamine,palmityl dipropanolamine, myristyl dipropanolamine, n-decyldiethanolamine, and lauryl diethanolamine.

Exemplary trialkyl amines include stearyl diethylamine, myristyldiethylamine, palmityl diethylamine, stearyl decyl octyl amine, stearylbutyl decyl amine, distearyl ethylamine, dipalmityl propylamine, behenyldimethylamine and isodecyl dibutylamine.

Exemplary dialkyl amines include stearyl ethyl amine, myristyl ethylamine, palmityl ethyl amine, stearyl decyl amine, stearyl butyl amine,stearyl methyl amine, palmityl propyl amine, behenyl methyl amine, andeicosyl methyl amine.

Exemplary monoalkyl amines include stearyl amine, myristyl amine,palmityl amine, oleyl amine, and behenyl amine.

The following Examples illustrate tris-organophosphite compositionshaving an improved hydrolytic stability in accordance with theinvention.

EXAMPLES 1 TO 4

To tris-nonylphenyl phosphite was added N-tallow diethanolamine (90%C-18, balance mainly C-16) in the amounts listed in Table I below.Homogeneous liquid blends were obtained in each Example.

The hydrolytic, stability of the phosphite compositions was determinedin terms of the days required for 50% decomposition to occurs as a 1.5gram sample of each phosphite composition was exposed in a humiditychamber at 100% relative humidity. The exposed phosphite composition wassampled periodically and analyzed by liquid chromatography. Thefollowing procedure was used.

A humidity chamber was set up using a large desiccator (SGA No. 1230,250 mm) with double-tiered plates. In the desiccator's well were put1500 ml of water to obtain 100% RH.

In aluminum weighing dishes (SGA No. 9000) there was placed theindicated quantity of the composition and, at a time zero, the disheswere placed inside the humidity chamber. Simultaneously, a LC analysiswas run at time zero. Later, on withdrawing samples for sequential LCanalyses the composition was thoroughly mixed inside the aluminum dishusing a spatula, before withdrawing the actual sample.

In a 2-gram vial (SGA No. 5250) there were weighed accurately 20 mg ofsample, also a micromagnetic stirring bar and 5 ml. (accuratelymeasured) of the LC solvent used (see below). The mixture was stirredfor 10 minutes on a magnetic stirring plate and filtered using a SampleClarification Kit (Waters catalog No. 26865). Exactly 10 mcl of thefiltered solution was injected using the LC parameters indicated below.

LIQUID CHROMATOGRAPHY

LC runs were carried out using a duPont modified-silica Zorbax-CN column(duPont No. 850952-705). Solvent, a 10-1 (v-v) mixture of isooctane-THF(LC grade), pumped at the rate of 1 ml/min. Chart speed: 0.5"/min.;detectors: Refractive Index att.×4 and U.V. (254 nm) at att.×0.1 AUFS.

CALCULATIONS

All calculations were carried out on the RI trace obtained. Peak heightswere measured (in mm.) from the base line. A "Response factor, f" wascalculated for each peak, using this equation ##EQU1##

This equation applies only when the weight is dissolved in 5-ml. ofsolvent and 10 mcl. are injected.

The change of "f" with time was followed. After total hydrolysis, the fvalues were normalized, assigning a value of 100 to the f value for thesample at time zero. The normalized values were plotted vs. time (inhours or days as indicated) to obtain the 50% decomposition time.

The following results were obtained:

                  TABLE I                                                         ______________________________________                                                Amount of N--                                                                 tallow diethanolamine                                                                           Hydrolytic stability                                Example % by weight of    (Days to 50%                                        No      phosphite         decomposition)*                                     ______________________________________                                        Control None              Less than one day                                   1       1                 3 days                                              2       3                 10 days                                             3       5                 Over 143 days                                                                 without change                                      4       1 + epoxy soybean oil 5%                                                                        Over 60 days                                                                  without change                                      ______________________________________                                         *100% RH, 1.5 g samples                                                  

As shown in Table I, the improvement by hydrolytic stability wascommensurate with the amount of amine additive. Example 1, thecomposition containing 1% N-n-octadecyl diethanolamine, gave ahydrolytic stability that was adequate to normal use. Example 2, thecomposition containing 3% of the amine, gave generous protection evenfor extreme conditions. Example 3, the composition containing 5% amine,and Example 4, the composition containing 1% amine together with 5%epoxidized soybean oil, gave a dramatic further improvement inhydrolytic stability as compared to the compositions containing 1% or 3%of the amine.

These results are far superior to those obtained using prior artadditives. To the same tris nonylphenyl phosphite used in Examples 1 to4 were added the additives shown in Table II below:

                  TABLE II                                                        ______________________________________                                                                   Hydrolytic stability                               Example Additive and % by  (days to 50%                                       No.     weight of phosphite                                                                              decomposition)*                                    ______________________________________                                        Control 1                                                                             Epoxy soyabean oil 5%                                                                             3                                                 Control 2                                                                             Tri-isopropanol amine                                                                             3                                                         0.5%                                                                  Control 3                                                                             Tri-isopropanol amine                                                                            4 to 7                                                     1%                                                                    Control 4                                                                             Epoxysoyabean oil 5%                                                                             11                                                         +0.5% tri-isopropanol amine                                           Control 5                                                                             Epoxysoyabean oil 5%                                                                             23                                                         +1% tri-isopropanol amine                                             ______________________________________                                         *100% RH, 1.25 g samples                                                 

As shown by comparing the results of Tables I and II, the hydrolyticstability of the phosphite has been dramatically improved by theaddition of long chain amine in accordance with the invention.

In separate experiments it has been shown that the hydrolytic stabilityof tris-nonylphenyl phosphite is independent of exposed sample size inthe range from 1 to 2 grams.

EXAMPLES 5 TO 11

N-coconut-alkyl diethanolamine (65% C-12, balance mainly C-14) was addedto samples of various phosphites in the amounts listed in Table IIIbelow. Homogeneous liquid blends resulted in each Example.

The hydrolytic stability of the phosphite compositions was determined interms of the days required for 50% decomposition to occur as 15 gramsamples of each phosphite composition were exposed in a humidity chamberat 100% relative humidity. Each exposed phosphite composition wassampled periodically and analyzed for trivalent phosphorus P (III) bytitration measuring the consumption of hydrogen peroxide as described inHecker U.S. Pat. No. 3,056,824. In this titration, each of thetriphosphites used consumes one mole of the oxidizing reagent H₂ O₂ permole of triphosphite while, on the other hand, hydrolytic fragments suchas phosphorous acid, monoalkyl or monoaryl phosphites, diphosphites etc.do not consume the oxidizing reagent. The titration, therefore,represents a measure of how much of the starting triphosphite has beenpreserved during the elapsed time of exposure to 100% relative humidity.

The following results were obtained:

                                      TABLE III                                   __________________________________________________________________________                                             Hydrolytic Stability                             Amine.sup.1 % by                                                                        Epoxide.sup.2 % by                                                                      Initial %                                                                              Days to 50%                          Example                                                                             Phosphite                                                                           weight of phosphite                                                                     weight of phosphite                                                                     P(III) by titration                                                                    decomposition                        __________________________________________________________________________    5     Triphenyl                                                                           1         none       9.45    5                                          phosphite                                                               6     Triphenyl                                                                           1         5         8.9      6                                          phosphite                                                               Control A   none      none      9.6      less than one day                    7     2-ethylhexyl                                                                        1         5         7.1      11                                         diphenyl                                                                      phosphite                                                               Control B   none      none      7.5      3                                    8     di-isodecyl                                                                         1         none      6.0      5                                          phenyl                                                                        phosphite                                                               9     di-isodecyl                                                                         3         none      6.2      9                                          phenyl                                                                        phosphite                                                               Control C   none      none      6.1      4                                    10    tris-nonyl-                                                                         1         5         3.8      more than                                  phenyl                             37.sup.3                                   phosphite                                                               11    tris-nonyl-                                                                         3         5         3.9      more than                                  phenyl                             37.sup.3                                   phosphite                                                               Control D   none      5         3.9      15                                   __________________________________________________________________________     .sup.1 Amine = coconutalkyl diethanolamine                                    .sup.2 Epoxide = epoxysoybean oil                                             .sup.3 On the 37th exposure day, titration showed more than 90% retention     of P(III) and the experiment was stopped.                                

The results show the very considerable improvement in hydrolyticstability of each phosphite with coconut-alkyldiethanolamine compared tothe same phosphite without the amine.

The phosphite amine compositions of the invention are effective,especially in combinations with other known stabilizers, in enhancingthe resistance to deterioration by heat and light of polyvinyl chlorideresins. The term "polyvinyl chloride" as used herein is inclusive of anypolymer formed at least in part of the recurring group: ##STR10## andhaving chlorine content in excess of 40%. In this group, the X groupscan each be either hydrogen or chlorine, and n is the number of suchunits in the polymer chain. In polyvinyl chloride homopolymers, each ofthe X groups is hydrogen. Thus, the term includes not only polyvinylchloride homopolymers but also after-chlorinated polyvinyl chlorides asa class, for example, those disclosed in British Pat. No. 893,288 andalso copolymers of vinyl chloride in a major proportion and othercopolymerizable monomers in a minor proportion, such as copolymers ofvinyl chloride and vinyl acetate, copolymers of vinyl chloride withmaleic or fumaric acids or esters, and copolymers of vinyl chloride withstyrene. The stabilizer compositions are effective also with mixtures ofpolyvinyl chloride in a major proportion with a minor proportion ofother synthetic resins such as chlorinated polyethylene or a copolymerof acrylonitrile, butadiene and styrene.

The phosphite and amine stabilizer compositions are applicable to thestabilization of rigid polyinvyl chloride resin compositions, that is,resin compositions which are formulated to withstand high processingtemperatures, of the order of 375° F. and higher, as well as plasticizedpolyvinyl chloride resin compositions of conventional formulation, eventhough resistance to heat distortion is not a requisite. Conventionalplasticizers well known to those skilled in the art can be employed,such as, for example, dioctyl phthalate, octyl diphenyl phosphate andepoxidized soybean oil.

Particularly useful plasticizers are the epoxy higher esters having from20 to 150 carbon atoms. Such esters will initially have had unsaturationin the alcohol or acid portion of the molecule, which is taken up by theformation of the epoxy group.

Typical unsaturated acids are acrylic, oleic, linoleic, linolenic,erucic, ricinoleic, and brassidic acids, and these may be esterifiedwith organic monohydric or polyhydric alcohols, the total number ofcarbon atoms of the acid and the alochol being within the range stated.Typical monohydric alcohols include butyl alcohol, 2-ethyl hexylalcohol, lauryl alcohol, isooctyl alcohol, stearyl alcohol, and oleylalcohol. The octyl alcohols are preferred. Typical polyhydric alcoholsinclude pentaerythritol, glycerol, ethylene glycol, 1,2-propyleneglycol, 1,4-butylene glycol, neopentyl glycol, ricinoleyl alcohol,erythritol, mannitol and sorbitol. Glycerol is preferred. These alcoholsmay be fully or partially esterified with the epoxidized acid. Alsouseful are the epoxidized mixtures of higher fatty acid esters found innaturally-occurring oils such as epoxidized soybean oil, epoxidizedolive oil, epoxidized coconut oil, epoxidized cotton-seed oil,epoxidized tall oil fatty acid esters and epoxidized tallow. Of these,epoxidized soybean oil is preferred.

The alcohol can contain the epoxy group and have a long or short chain,and the acid can have a short or long chain, such as epoxystearylacetate, epoxystearyl stearate, glycidyl stearate, and polymerizedglycidyl methacylate.

The polyvinyl chloride resin can be in any physical form, including, forexample, powders, films, sheets, molded articles, foams, filaments andyarns.

A sufficient amount of the phosphite and amine stabilizer composition isused to enhance the resistance of the polyvinyl chloride todeterioration in physical properties, including, for example,discoloration and embrittlement, under the heat and/or light conditionsto which the polymer will be subjected. Very small amounts are usuallyadequate. Amounts within the range from about 0.01 to about 5% of thephosphite and from about 0.01 to about 10% of other stabilizers byweight of the polyvinyl chloride resin are satisfactory. Preferably, anamount within the range from about 0.05 to about 2% of phosphite, andfrom about 0.1 to about 5% of other stabilizer is employed for optimumstabilizing effectiveness.

The phosphite and amine stabilizer compositions of the invention can beemployed as the sole stabilizers. They can also be used in combinationwith other conventional heat and light stabilizers for polyvinylchloride resins, such as, for example, polyvalent metal salts andalkaline earth metal phenolates, as well as epoxy compounds.

A particularly useful stabilizer system contains the following amountsof ingredients:

(a) phosphite in an amount within the range from about 25 to about 45parts by weight;

(b) phenolic antioxidant in an amount within the range from about 0.01to about 1 part by weight;

(c) polyvalent metal salt of an aliphatic carboxylic acid or of an alkylphenol in an amount within the range from about 25 to about 45 parts byweight; plus any one or more of the following optional ingredients:

(d) free aliphatic carboxylic acid in an amount within the range fromabout 0.5 to about 5 parts by weight; and

(e) acid phosphite in an amount within the range from about 0.5 to about5 parts by weight.

In addition, any of the conventional polyvinyl chloride resin additives,such as lubricants, emulsifiers, antistatic agents, flame-proofingagents, pigments and fillers, can be employed.

Preferably, the stabilizer system is added to the polyvinyl chlorideresin in an amount to provide in the resin from about 0.2 to about 1% ofthe phosphite; from about 0.1 to about 2% of phenolic antioxidant; andfrom about 0 to about 1% total of one or more of the additionalingredients, as noted above.

The stabilizer system is incorporated in the polymer in suitable mixingequipment, such as a mill or a Banbury mixer. Mixing is continued untilthe mixture is substantially uniform. The resulting composition is thenremoved from the mixing equipment and brought to the size and shapedesired for marketing or use.

The stabilized polyvinyl chloride resin can be worked into the desiredshape, such as by milling, calendering, extrusion or injection molding,or fiber-forming. In such operations, it will be found to have aconsiderably improved resistance to discoloration and embrittlement onexposure to heat and light.

The phosphite and amine stabilizer compositions of the invention areespecially effective heat stablizers for olefin polymers such aspolyethylene, polypropylene, polybutylene, polpentylene,polyisopentylene, and higher polyolefins, and copolymers of two or moreolefins.

Olefin polymers on exposure to elevated temperatures undergodegradation, resulting in embrittlement and discoloration.

The phosphite and amine stabilizer compositions can be employed with anyolefin polymer, including low-density polyethylene, high densitypolyethylene, polyethylenes prepared by the Ziegler-Natta process,copolymers of ethylene with minor amounts of propylene butene-1,hexene-1, n-octene-1, including so-called linear low densitypolyethylene, polypropylene prepared by the Ziegler-Natta process, andby other polymerization methods from propylene, poly(butene-1),poly(pentene-1, poly(3-methylbutene-1), poly(4-methylpentene-1),polystyrene, and mixtures of polyethylene and polypropylene with othercompatible polymers, such as mixtures of polyethylene and polypropylene,and all copolymers of such olefins, such as copolymers of ethylene,propylene, and butene, with each other and with other copolymerizablemonomers. The term "olefin polymer" encompasses both homopolymers andcopolymers.

The preferred olefin polymers in which the phosphite amine compositionsof this invention are effective include polypropylene manufactured bythe catalytic polymerization of propylene and having a density of 0.880to 0.913 g/ml and a melting point or softening point from 160° to 180°C.; polyethylene manufactured by the catalytic polymerization ofethylene and having a density of 0.85 to 1.00 g/ml and a 5.5% maximumextractable fraction in n-hexane at 50° C.; poly(methylpentene)manufactured by the catalytic polymerization of 4-methylpentene-1 andhaving a density of 0.82 to 0.85 g/ml and a melting point from 235° to250° C., olefin copolymers manufactured by the catalyticcopolymerization of two or more 1-alkenes having 2 to 8 carbons (except4-methylpentene-1) having a density of 0.85 to 1.0 and a 5.5% maximumextractable fraction in n-hexane at 50° C; and copolymers of4-methylpentene-1 and a 1-alkene having 6 to 10 carbon atoms having adensity of 0.82 to 0.85 g/ml and a melting point of 235° to 250° C.

The phosphite and amine stabilizer compositions are also effective toenhance the resistance to heat degradation of polystyrene; polydienes,such as polybutadiene and polyisoprene; and copolymers of olefins anddienes with other ethylenically and acetylenically unsaturated monomers,such as ethylene-vinyl acetate copolymers, styrene-butadiene copolymers,acrylonitrile-styrene-butadiene copolymers, synthetic rubbers of alltypes, such as polychloroprene; polyvinylidene chloride; and copolymersof vinyl chloride and vinylidene chloride; vinylidene chloride and vinylacetate; and other ethylenically unsaturated monomers; polyacetals suchas polyoxymethylene and polyoxyethylene; polycarbonates; polyphenyleneoxides; polyesters such as polyethylene glycolterephthalic acid esterpolymers; polyamides such as polyepsilon-caprolactam; polyhexamethyleneadipamide and polydecamethylene adipamide; polyurethanes; and epoxyresins.

The synthetic polymer can be in any physical form, including, forexample, filaments, yarns, films, sheets, molded articles, latex andfoam.

A sufficient amount of the stabilizer composition including thephosphite and amine is used to improve the resistance of the syntheticpolymer to deterioration in physical properties, including, for example,discoloration, objectionable change in melt viscosity and embrittlement,under the conditions to which the polymer will be subjected. Very smallamounts are usually adequate. Amounts within the range from about 0.001to about 5% total stabilizers by weight of the polymer are satisfactory.Preferably, from 0.01 to 3% is employed, for optimum stabilization.

The phosphite and amine compositions of the invention can be employed asthe sole stablizers or in combination with other conventional heat andlight stabilizers for the particular olefin polymer.

Thus, for example, there can be employed fatty acid salts of polyvalentmetals, and the higher fatty alkyl esters of thiodipropionic acids, suchas, for example, dilauryl thiodipropionate.

With polyamide resin compositions, polyamide stabilizers such as coppersalts in combination with iodides and/or other phosphorus compounds andsalt of divalent manganese can be used.

With synthetic rubbers and acrylonitrile-butadiene-styrene terpolymers,polyvalent metal salts of higher fatty acids can be used.

In addition, other conventional additives for synthetic polymers, suchas plasticizers, lubricants, emulsifiers, antistatic agents,flame-proofing agents, pigments and fillers, can be employed.

The stabilizer composition is incorporated in the polymer in suitablemixing equipment, such as a mill or a Banbury mixer. If the polymer hasa melt viscosity which is too high for the desired use, the polymer canbe worked until its melt viscosity has been reduced to the desired rangebefore addition of the stabilizers. Mixing is continued until themixture is substantially uniform. The resulting composition is thenremoved from the mixing equipment and brought to the size and shapedesired for marketing or use.

The stabilized polymer can be worked into the desired shape, such as bymilling, calendering, extruding or injection molding or fiber-forming.In such operations, it will be found to have a considerably improvedresistance to reduction in melt viscosity during the heating, as well asa better resistance to discoloration and embrittlement on ageing andheating.

The following Examples represent preferred embodiments of syntheticresin compositions containing phosphite amine compositions of theinvention.

EXAMPLE 12

Polyvinyl chloride resin compositions having the following formulationwere prepared:

    ______________________________________                                                         Parts by Weight                                                               Example 12                                                                            Control                                              ______________________________________                                        Vinyl chloride homopolymer                                                                       100       100                                              (Geon 110 × 450)                                                        Dialkyl phthalate  43        43                                               (Santicizer 711)                                                              Epoxysoybean oil   7         7                                                Phosphite/amine    0.2       --                                               composition of Example 3                                                      Zinc stearate      0.15      0.25                                             Calcium stearate   0.12      0.19                                             2,6-di-t-butyl-p-cresol                                                                          0.038     0.06                                             ______________________________________                                    

The compositions were milled on a two-roll mill at 350° F. for threeminutes, and then sheeted off. The milled sheets were cut into strips,which were then placed in an oven and heated at 350° (177° C.) or 375°F. (190° C.) until dark edges appeared on the samples. Samples of eachwere cut off from the strips at 10 minute intervals, and placed on acard. The times required for the samples to yellow and to develop darkedges were noted, and are reported below in Table IV.

    ______________________________________                                                         Example 12                                                                            Control                                              ______________________________________                                        Oven heat stability 350° F.                                            Minutes to yellow    90      15                                               Minutes to dark edge                                                                             >120      120                                              Oven heat stability 375° F.                                            Minutes to yellow    30      10                                               Minutes to dark edge                                                                               70      50                                               ______________________________________                                    

Samples also were molded into panels 0.050 inch thick, and the yellowindex determined according to ASTM D 1925-70 using a Hunter colorimeterand the following results:

    ______________________________________                                                         Example 12                                                                             Control                                             ______________________________________                                        Color of 0.050" molding,                                                      Hunter colorimeter                                                            Yellow index, ASTM D 1925-70                                                                      2.02      3.94                                            ______________________________________                                    

The lower Yellow Index values signify less yellow and hence preferablesamples. Example 5 is clearly superior.

EXAMPLE 13

Polypropylene compositions were prepared, having the followingformulation:

    ______________________________________                                                         Parts by Weight                                                               Example 13                                                                            Control                                              ______________________________________                                        Polypropane        100       100                                              (Profax 6501)                                                                 Calcium stearate   0.1       0.1                                              Phosphite amine composition                                                                      0.05      --                                               of Example 3                                                                  ______________________________________                                    

The additives were blended with the polypropylene powder in a hexaneslurry, and the hexane removed under vacuum in a rotary evaporator. Theresulting blend was fed to an extruder, from which the material exitedas a continuous strand. This was passed through a water cooling bath andchopped into pellets, which were collected and reextruded for a total ofseven successive extrusions for each sample. In the first extrusion, thefollowing temperature profile was used:

Zone 1--375° F.

Zone 2--410° F.

Zone 3--450° F.

Die--450° F.

In the subsequent extrusions, all zones were at 450° F.

Samples were taken from the first, third, fifth and seventh extrusionand molded into 0.02 inch (0.5 mm) thick panels. The melt flow index(MI, ASTM D 1238) and color (Hunter colorimeter yellow index, YI, ASTM D1925) was determined for each sample. The results are tabulated in TableV.

                  TABLE V                                                         ______________________________________                                                          Control 2        Example 13                                                   TNPP.sup.1                                                                             Control 3                                                                             TNPP.sup.1 + 5%                                     Control 1                                                                              without  TNPP.sup.1 +                                                                          tallow-alkyl                               Stabilizer                                                                             None     amine    1% TIPA.sup.2                                                                         diethanolamine                             ______________________________________                                        First                                                                         extrusion                                                                     MI       3.2       1.8      1.2    1.5                                        YI       9.1      12.6     12.2    6.5                                        3rd extrusion                                                                 MI       3.3       3.7      2.7    1.9                                        YI       13.5     10.8     13.5    11.3                                       5th extrusion                                                                 MI       4.4       4.0      3.7    2.2                                        YI       14.0     10.7     16.1    12.3                                       7th extrusion                                                                 MI       5.6       5.6      4.6    3.0                                        YI       13.6     12.0     15.2    12.0                                       ______________________________________                                    

Both MI and YI are desirably as low as possible. It can easily be seenthat only Example 13, the sample containing TNPP with the tallowdiethanolamine additive is consistently better in both MI and YI than acontrol without phosphite (left hand column) while TNPP without amine orwith TIPA added is at best marginally effective and somewhatinconsistent.

EXAMPLES 14 to 18

Linear low-density polyethylene compositions were prepared having thefollowing formulation:

    ______________________________________                                                        Parts by Weight                                                               Examples 14 to 18                                                                         Control                                           ______________________________________                                        Linear low-density polyethylene                                                                 100           100                                           (Dow LLDPE, density 0.919,                                                    melt index 1.1)                                                               Calcium stearate  0.02          0.02                                          Phosphite amine composition                                                                     As shown in   none                                          of Example 3      Table VI                                                    Phenolic antioxidants listed                                                                    0.025 (when   none                                          in Table VI       present)                                                    ______________________________________                                    

The additives were blended with the linear low-density polyethylenegranules in a hexane slurry, and the hexane removed under vacuum in arotary evaporator. The resulting blend was fed to an extruder, fromwhich the material exited as a continuous strand. This was passedthrough a water cooling bath and chopped into pellets, which werecollected and reextruded for a total of seven successive extrusions foreach sample. In the first extrusion, the following temperature profilewas used:

Zone 1--360° F.

Zone 2--380° F.

Zone 3--400° F.

Die--400° F.

In the subsequent extrusions, all zones were at 430° F.

Samples were taken from the first, third, fifth and seventh extrusionand molded into 0.02 inch (0.5 mm) thick panels. The 190° C. melt index(MI, ASTM D 1238) and color (Hunter colorimeter yellow index, YI, ASTM D1925) was determined for each sample. The results are tabulated in TableVI.

                                      TABLE VI                                    __________________________________________________________________________    Phosphite-Amine     Extrusion No.                                             Composition,  Phenolic                                                                            1      3      5     7                                     Example                                                                            Parts by Weight                                                                        Antioxidant                                                                         MI YI  MI YI  MI YI MI YI                                 __________________________________________________________________________    Control                                                                            none     none   0.86                                                                            -4.1                                                                              0.53                                                                             -1.1                                                                              0.46                                                                             2.6                                                                              0.40                                                                             5.2                                14   0.05     none   0.99                                                                             -0.53                                                                            0.83                                                                             +7.0                                                                              0.69                                                                             9.5                                                                              0.63                                                                             8.9                                15   0.025    A 0.025                                                                             1.0                                                                              -2.5                                                                              0.90                                                                             3.9 0.85                                                                             13.6                                                                             0.83                                                                             19.3                               16   0.025    B 0.025                                                                             1.0                                                                               -0.18                                                                            0.99                                                                             3.3 1.0                                                                              5.1                                                                              1.0                                                                              7.8                                17   0.025    C 0.025                                                                             1.0                                                                              -2.1                                                                              0.79                                                                             3.0 0.62                                                                             3.3                                                                              0.54                                                                             5.3                                18   0.025    D 0.025                                                                             1.0                                                                              -2.9                                                                              0.99                                                                             -0.41                                                                             0.88                                                                             3.5                                                                              0.79                                                                             4.9                                __________________________________________________________________________     Phenolic Antioxidants:                                                        A = 2,2ethylidenebis(4,6-di-t-butylphenol)                                    B =                                                                           1,3,5tris(4-t-butyl-3hydroxy-2,6-dimethylbenzyl)-1,3,5-tri-azine-2,4,5(1H    3H,5H)trione                                                                   C = Octadecyl 3,5di-t-butyl-4-hydroxy hydrocinnannate                         D = Pentaerythrityl tetrakis (3,5di-t-butyl-4-hydroxy hydrocinnannate    

Unlike polypropylene, linear low-density polyethylene degrades bycross-linking and, as a result, the melt index decreases. Theeffectiveness of the phosphite-amine composition in Example 14, and ofthe combinations thereof with phenolic antioxidants in Examples 15 to 18in minimizing this decrease is evident from the results presented. Atthe same time, good color protection is also obtained with thecompositions of this invention.

Having regard to the foregoing disclosure the following is claimed asthe inventive and patentable embodiments thereof: 1.Tris-organophosphite compositions having an improved hydrolyticstability, comprising(1) a tris-organophosphite of the formula:##STR11## wherein: R₁, R₂ and R₃ are selected from the group consistingof alkyl, alkenyl, aryl, alkylaryl and aralkyl groups togetheraggregating at least fourteen carbon atoms up to about sixty carbonstoms; and (2) a long-chain aliphatic amine in an amount to improve thehydrolytic stability of the phosphite and having the formula: ##STR12##wherein: R₄, R₅ and R₆ are selected from the group consisting ofhydrogen; aliphatic groups having from one to about thirty-six carbonatoms; and hydroxyalkyl having from two to about six carbon atoms; oneof R₄, R₅ and R₆ is an aliphatic group having at least ten carbon atoms,and the remaining of R₄, R₅ and R₆ are selected from hydrogen, alkylhaving from one to four carbon atoms and hydroxyalkyl. 2.Tris-organophosphite compositions according to claim 1 in which R₁, R₂and R₃ are alkyl.
 3. Tris-organophosphite compositions according toclaim 1 in which R₁, R₂ and R₃ are alkylaryl.
 4. Tris-organophosphitecompositions according to claim 3 in which R₁, R₂ and R₃ arenonylphenyl.
 5. Tris-organophosphite compositions according to claim 1in which the amine is an aliphatic hydrocarbyl amine. 6.Tris-organophosphite compositions according to claim 1 in which theamine is an aliphatic amine having at least one hydroxyalkyl group. 7.Tris-organophosphite compositions according to claim 1 in which theamine is an aliphatic amine wherein one of R₄, R₅ and R₆ is hydrogen. 8.Tris-organophosphite compositions according to claim 1 in which theamine is an aliphatic amine wherein two of R₄, R₅ and R₆ are hydrogen.9. Tris-organophosphite compositions according to claim 1 in which theamine is an aliphatic amine wherein one of R₄, R₅ and R₆ is alkyl of oneto four carbon atoms.
 10. Tris-organophosphite compositions according toclaim 1 in which the amine is an aliphatic amine wherein two of R₄, R₅and R₆ are alkyl of one to four carbon atoms.
 11. Tris-organophosphitecompositions according to claim 1 in which the amine is an aliphaticamine having two hydroxyalkyl groups.
 12. Tris-organophosphitecompositions according to claim 11 in which the hydroxyalkyl ishydroxyethyl.
 13. Tris-organophosphite compositions according to claim12 in which the amine is N-n-octadecyl diethanolamine.